Jn recent months, car sales figures are reaching new heights and Indians are buying cars equipped with various features. Recently, Hyundai revealed that one in three cars sold in the first half of 2022 had a sunroof. But that same slide contained another fascinating statistic: one in five Hyundai cars sold in India had an automatic transmission. In fact, over 10% of all passenger cars sold in India were fitted with some form of automatic transmission.
But what do I mean by “a kind of automatic”? It’s a common misconception that all automatic transmissions are the same. It’s an alphabet soup of acronyms for different kinds of automatic transmissions. Although all “automatic” transmissions remove the need to physically operate the clutch pedal, there is still a clutch in the vehicle. Sort of, anyway. The traditional “torque-converter” automatic has a “wet clutch” and the dual-clutch has, as the name suggests, not one but two clutch pedals.
So let me start explaining the different technologies, starting with the traditional torque converter. Now, to be fair, when I say traditional, I don’t mean that these gearboxes are now “old fashioned”. Thanks to advances in modern machining and metallurgy and even hydraulic fluids, modern torque converters are extremely efficient. Simply put, a torque converter is a fluid coupling, the engine driveshaft spins a vane which spins hydraulic fluid which then feeds a driveshaft. This is a hydrokinetic system, and although there are extremely complicated fluid dynamics here, the torque converter manages the loads on the driveshaft, either to increase or reduce the amount of torque to the drive wheels.
The first PLCs were developed in the 1930s, long before the advent of microprocessors. And back then, automatics usually only had two speeds – slow and fast. In fact, three- and four-speed automatics were standard until a decade ago, when manual transmissions already had five or six speeds.
These older automatic transmissions, while removing the labor of clutch actuation, were not as economical as manuals. In fact, they were much thirstier. The old Maruti Zen automatic as well as the first WagonR automatic were three-speed automatics. Today vehicles like the Maruti-Suzuki XL6 and Brezza, diesel variants of the Creta, Carens and Seltos all have torque converters. Like most BMWs, which use an eight-speed transmission developed by the German firm ZF.
The internal mechanics of a torque converter are extremely complex and everything, like the rest of any modern car, is controlled by microprocessors. This is why on most modern cars, automatic torque converters are actually as efficient, if not more efficient, than manual ones.
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The many automatic
While in America automakers pushed automatics during the post-war economic boom of the 1950s thanks to cheap “gasoline”, in India automatics really started to take off a while ago. about a decade when Maruti-Suzuki introduced the first Celerio with an “automated manual”. Transmission’ (AMT). Again, it does what it says on the acronym. Think of an AMT as a robotic replacement for your left foot that operates the clutch and a robotic left hand that shifts gears.
AMT technology matured in the 1980s as a low cost solution to the complex mechanics of a torque converter. Even today, AMTs are cheap. That is why they are offered on all Maruti sedans, Hyundai i10 Nios, Tata Tiago and Tigor and some other cars. Having driven many of these over the years, let me assure you that they are not the most enthusiastic vehicles to drive and the shifting is lazy at best. But, they get the job done and when you’re stuck in a two hour traffic jam at the Silk Board Junction in Bengaluru, performance isn’t what you care about, resting your left calf muscles is all that matters.
In order to bring back some of the excitement for these vehicles, Hyundai and Kia have “Intelligent Manual Transmission” or IMT where a driver can physically manipulate the gears and although the shifts are not as crisp as a quick manual shift, this brings back a manual override item.
But what about the continuously variable transmission (CVT) on the Honda City or, as Hyundai-Kia calls it, the ‘IVT’ on the Creta, Seltos and Verna? Well, to explain this simply, take two ice cream cones facing each other and tie a rubber band between them. Then, as these two cones slide up and down, the amount of power transmitted if you spin one cone to the other cone changes. Please don’t use this explanation in your engineering exam, it’s not even the Cliff Notes version. But yeah, that’s pretty much how it works.
On some cars there are usually “steps” between the cones (like on Hondas) and while CVTs aren’t fun to drive at all if you want to get high, they are extremely economical. For much of the second lockdown last year I was driving the Hyundai Verna IVT and even in city driving conditions the car delivered 15-16 kilometers per liter with ease.
Then you get the Dual Clutch Transmission (DCT) or, as the Volkswagen Group calls it, the Direct Shaft Transmission or ‘Direktschalgetriebe‘ (DSG, it was invented by Porsche). Such gearboxes are present on the new Skoda Kushaq and Slavia as well as on the Volkswagen Taigun and Virtus among others. Hyundai and Kia also offer them on the i20, Creta and Seltos. Simply put, there are two driveshafts on two clutches on cars with such transmissions, one for odd gears and one for even gears and reverse.
This is also why DCT cars almost always have an odd number of forward gears. The unused driveshaft is already ready for action. That’s why DCT shifts are faster than you can blink. In terms of driving pleasure, DCTs are on another level, as anyone who has even driven the i20 with a DCT can attest, but modern torque converters are also very good. In fact, the extreme power levels of cars like the Mercedes-Benz AMG and BMW M cars mean that DCTs have been replaced by torque converters because they can handle the power.
But none of these gearboxes were the most advanced you can buy in India, unfortunately this gearbox is no longer available. It was the 10-speed triple-clutch transmission that had been offered for just over 18 months on the latest models of the Ford Endeavor in India. This crazy gearbox was jointly developed by Ford and General Motors and when I drove it on a Ford F150 in Detroit for the first time in 2016, I was blown away. In India, it looked like too many gears, the car was always going through the gears in traffic, but every time you saw the speedometer indicating that you were on “tenth gear”, it seemed weird to you. Too bad Ford had to leave India.
@kushanmitra is an automotive journalist based in New Delhi. Views are personal.
(Edited by Prashant)